There has been a continuing need for extrudable elastomeric compositions which can be easily extruded into elastic sheets having low stress relaxation, low hysteresis and high recoverable energy. This need has persisted in spite of the fact that such elastic sheets could readily be utilized in the manufacture of a wide variety of garments of both the disposable type, such as disposable diapers, or the durable type, such as pants, dresses, blouses and sporting wear, for example, sweatsuits. Further, such elastic sheets could also be utilized in, for example, upholstery, draper, liner and insulation applications. The traits of low initial load tension, low stress relaxation, low hysteresis and high recoverable energy are particularly desirable characteristics for elastic sheets used in these areas because articles manufactured from such materials may be easily put on the body of the wearer or any item, such as a fixed frame, around which the materials may be wrapped. Those traits are also very useful because articles manufactured from such materials are able to closely conform to the body of a wearer or any item and repeatedly extend and retract without sagging.
Styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers have been blended with other materials such as, for example, polyolefins and tackifying resins to form extrudable elastomeric compositions which can be more easily extruded into elastic sheets having improved processing and/or bonding properties. While the additives improve the extrusion properties of the compositions and the processing and/or bonding properties of the elastic sheet, such additives may, in certain situations, have an adverse affect on the elastic properties of the resulting sheet. For example, such elastomeric block copolymers blended with large amounts of a polyolefin and/or hydrocarbon resin may have poor stress relaxation properties and stress-strain tests of such materials show significant hysteresis.